U.S. patent application number 14/600858 was filed with the patent office on 2016-07-21 for radial coverage piston ring groove arrangement.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. The applicant listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to Jonathan Logan Miller.
Application Number | 20160208923 14/600858 |
Document ID | / |
Family ID | 55229546 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160208923 |
Kind Code |
A1 |
Miller; Jonathan Logan |
July 21, 2016 |
RADIAL COVERAGE PISTON RING GROOVE ARRANGEMENT
Abstract
A main shaft bearing compartment seal system is described
herein. The modified ring groove geometry creates two distinct
cavities or steps for a piston ring and a wave spring. This concept
provides a separate groove cavity for the spring independent of the
fool-proofing and clearance cavity. This modified ring groove
geometry increases first face coverage and reduces exposure risk
for eccentricity of wave spring to piston ring, to avoid potential
disengagement and improve function and performance of the seal
assembly and engine.
Inventors: |
Miller; Jonathan Logan;
(Ware, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
Hartford |
CT |
US |
|
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
55229546 |
Appl. No.: |
14/600858 |
Filed: |
January 20, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16J 15/3268 20130101;
F01D 11/003 20130101; F16J 15/441 20130101; F16J 15/3208 20130101;
F16J 15/3252 20130101 |
International
Class: |
F16J 15/32 20060101
F16J015/32; F01D 11/00 20060101 F01D011/00 |
Claims
1. A main shaft bearing compartment seal system comprising: a
cylindrical inner diameter (ID) bore; a carbon seal assembly
juxtaposed substantially adjacent to a portion of the cylindrical
ID bore, wherein the carbon seal assembly comprises a first step
and a second step; a piston ring, wherein the piston ring is
cylindrical and substantially surrounds the cylindrical ID bore;
and a spring configured to interface with a surface of the piston
ring.
2. The main shaft bearing compartment seal system of claim 1,
wherein dimensions of the piston ring provide resistance to
improper installation.
3. The main shaft bearing compartment seal system of claim 1,
wherein the spring is a wave spring.
4. The main shaft bearing compartment seal system of claim 1,
wherein a piston ring face configured to interface with spring face
is longer, measured radially, than a radial length of the spring
face.
5. The main shaft bearing compartment seal system of claim 1,
wherein a width of the second step is sized to prevent the spring
from entering a gap formed between the piston ring and the carbon
seal assembly.
6. The main shaft bearing compartment seal system of claim 1,
wherein in response to the carbon seal assembly bottom contacting
at one circumferential location, the interface between a piston
ring face and a spring face is no less than 66% coverage.
7. The main shaft bearing compartment seal system of claim 1,
wherein dimensions of the first step of the carbon seal assembly
provide resistance to improper installation.
8. A carbon seal assembly comprising: a first step; and a second
step, wherein the carbon seal assembly is juxtaposed substantially
adjacent to a portion of a cylindrical inner diameter (ID) bore,
wherein a piston ring is configured to interface with a face of the
carbon seal assembly, wherein the piston ring is cylindrical and
substantially surrounds the cylindrical ID bore, and wherein a
spring is configured to interface with a surface of the piston
ring.
9. The carbon seal assembly of claim 8, wherein dimensions of the
piston ring provide resistance to improper installation.
10. The carbon seal assembly of claim 8, wherein the spring is a
wave spring.
11. The carbon seal assembly of claim 8, wherein a piston ring face
configured to interface with a spring face is longer than the
spring face.
12. The carbon seal assembly of claim 8, wherein a width of the
second step is sized to prevent the spring from entering a gap
formed between the piston ring and the carbon seal assembly.
13. The carbon seal assembly of claim 8, wherein in response to the
carbon seal assembly bottom contacting at one circumferential
location, the interface between the face of the piston ring and the
spring is no less than 66% coverage.
14. The main shaft bearing compartment seal system of claim 1,
wherein dimensions of the first step of the carbon seal assembly
provide physical fool proofing.
15. A piston ring comprising: a first face configured to form a
first seal between the piston ring and a cylindrical ID bore; a
second face configured to form a second seal between the piston
ring and a carbon seal assembly; and a third face configured to
interface with a surface of a spring, wherein the third face is
longer than the surface of the spring.
16. The piston ring of claim 15, wherein the spring is a wave
spring.
17. The piston ring of claim 15, wherein the carbon seal assembly
comprises a first step and a second step.
18. The piston ring of claim 17, wherein a width of the second step
is sized to prevent a portion of the spring from entering a gap
formed between the piston ring and the carbon seal assembly.
19. The piston ring of claim 17, wherein dimensions of the first
step of the carbon seal assembly provide resistance to improper
installation.
20. The piston ring of claim 15, wherein in response to the carbon
seal assembly bottom contacting at one circumferential location,
the interface between a face of the piston ring and the spring is
no less than about 66% coverage of contact between a face of the
piston ring and the surface of the spring.
Description
FIELD
[0001] The present disclosure relates to seals and more
particularly to main shaft bearing compartment seals.
BACKGROUND
[0002] A conventional main shaft bearing compartment seal system
100 is depicted in FIG. 1B. Notably, system 100 includes a
traditional piston ring and wave spring within a groove assembly.
In response to radial eccentricity of each part in the opposite
respective radial directions, the radial coverage is low between a
piston ring face and a wave spring face. Having low values of face
coverage may cause wave spring distortion. This could negatively
impact the function and performance of the seal assembly and
engine.
SUMMARY
[0003] According to various embodiments, a main shaft bearing
compartment seal system is described herein. The system may include
a cylindrical ID bore. The system may include a carbon seal
assembly juxtaposed substantially adjacent to a portion of the
cylindrical ID bore. The carbon seal assembly may comprise a first
step and a second step. The system may include a piston ring,
wherein the piston ring is cylindrical and substantially surrounds
the cylindrical ID bore. The system may include a spring configured
to interface with a surface of the piston ring. Dimensions of the
piston ring may provide physical fool proofing. The spring may be a
wave spring. A piston ring face configured to interface with spring
face may be longer than the spring face.
[0004] A width of the second step may be sized to prevent the
spring from entering a gap formed between the piston ring and the
carbon seal assembly. According to various embodiments, in response
to the carbon seal assembly bottom contacting at one
circumferential location, the interface between a piston ring face
and a spring face may be maintained to acceptable levels, for
instance the interface between the piston ring face and the spring
face may be no less than 66% coverage. Dimensions of the first step
of the carbon seal assembly provide physical fool proofing.
[0005] According to various embodiments, a carbon seal assembly is
disclosed herein. The carbon seal assembly may include a first
step; and a second step or a first groove and a second groove. The
carbon seal assembly may be juxtaposed substantially adjacent to a
portion of a cylindrical ID bore. A piston ring may be configured
to interface with a face of the carbon seal assembly. The piston
ring may be cylindrical and substantially surrounds the cylindrical
ID bore, and wherein a spring may be configured to interface with a
surface of the piston ring.
[0006] According to various embodiments, a piston ring is described
herein. The piston ring may include a first face configured to form
a first seal between the piston ring and a cylindrical ID bore. The
piston ring may include a second face configured to form a second
seal between the piston ring and a carbon seal assembly. The piston
ring may include a third face configured to interface with a
surface of a spring. The third face may be longer than the surface
of the spring.
[0007] The forgoing features and elements may be combined in
various combinations without exclusivity, unless expressly
indicated herein otherwise. These features and elements as well as
the operation of the disclosed embodiments will become more
apparent in light of the following description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The subject matter of the present disclosure is particularly
pointed out and distinctly claimed in the concluding portion of the
specification. A more complete understanding of the present
disclosure, however, may best be obtained by referring to the
detailed description and claims when considered in connection with
the drawing figures, wherein like numerals denote like
elements.
[0009] FIG. 1A is a cross-sectional view of a gas turbine engine,
in accordance with various embodiments;
[0010] FIG. 1B depicts a conventional main shaft bearing
compartment seal system;
[0011] FIGS. 2A-2D depict isometric and isometric cut-away views of
an improved radial coverage piston ring groove arrangement in
accordance with various embodiments;
[0012] FIG. 2E depicts a cross-sectional cut-away side view of an
improved radial coverage piston ring groove arrangement in
accordance with various embodiments; and
[0013] FIG. 3 depicts an improved radial coverage piston ring
groove arrangement with a non-centered carbon seal assembly in
accordance with various embodiments.
DETAILED DESCRIPTION
[0014] The detailed description of exemplary embodiments herein
makes reference to the accompanying drawings, which show exemplary
embodiments by way of illustration. While these exemplary
embodiments are described in sufficient detail to enable those
skilled in the art to practice the inventions, it should be
understood that other embodiments may be realized and that logical,
chemical and mechanical changes may be made without departing from
the spirit and scope of the inventions. Thus, the detailed
description herein is presented for purposes of illustration only
and not of limitation. For example, the steps recited in any of the
method or process descriptions may be executed in any order and are
not necessarily limited to the order presented. Furthermore, any
reference to singular includes plural embodiments, and any
reference to more than one component or step may include a singular
embodiment or step. Also, any reference to attached, fixed,
connected or the like may include permanent, removable, temporary,
partial, full and/or any other possible attachment option.
Additionally, any reference to without contact (or similar phrases)
may also include reduced contact or minimal contact.
[0015] Different cross-hatching and/or surface shading may be used
throughout the figures to denote different parts but not
necessarily to denote the same or different materials.
[0016] FIG. 1A schematically illustrates an example gas turbine
engine 20 that includes a fan section 22, a compressor section 24,
a combustor section 26 and a turbine section 28. Alternative
engines might include an augmenter section (not shown) among other
systems or features. The fan section 22 drives air along a bypass
flow path B while the compressor section 24 draws air in along a
core flow path C where air is compressed and communicated to a
combustor section 26. In the combustor section 26, air is mixed
with fuel and ignited to generate a high pressure exhaust gas
stream that expands through the turbine section 28 where energy is
extracted and utilized to drive the fan section 22 and the
compressor section 24.
[0017] Although the disclosed non-limiting embodiment depicts a
turbofan gas turbine engine, it should be understood that the
concepts described herein are not limited to use with turbofans as
the teachings may be applied to other types of turbine engines; for
example a turbine engine including a three-spool architecture in
which three spools concentrically rotate about a common axis and
where a low spool enables a low pressure turbine to drive a fan via
a gearbox, an intermediate spool that enables an intermediate
pressure turbine to drive a first compressor of the compressor
section, and a high spool that enables a high pressure turbine to
drive a high pressure compressor of the compressor section.
[0018] The example gas turbine engine 20 generally includes a low
speed spool 30 and a high speed spool 32 mounted for rotation about
an engine central longitudinal axis X relative to an engine static
structure 36 via various bearing systems 38. It should be
understood that various bearing systems 38 at various locations may
alternatively or additionally be provided.
[0019] The low speed spool 30 generally includes an inner shaft 40
that connects a fan 42 and a low pressure (or first) compressor 44
section to a low pressure (or first) turbine 46 section. The inner
shaft 40 drives the fan 42 through a speed change device, such as a
geared architecture 48, to drive the fan 42 at a lower speed than
the low speed spool 30. The high speed spool 32 includes an outer
shaft 50 that interconnects a high pressure (or second) compressor
52 section and a high pressure (or second) turbine section 54. The
inner shaft 40 and the outer shaft 50 are concentric and rotate via
the various bearing systems 38 about the engine central
longitudinal axis X.
[0020] A combustor 56 is arranged between the high pressure
compressor 52 and the high pressure turbine 54. In one example, the
high pressure turbine 54 includes at least two stages to provide a
double stage high pressure turbine 54. In another example, the high
pressure turbine 54 includes only a single stage. As used herein, a
"high pressure" compressor or turbine experiences a higher pressure
than a corresponding "low pressure" compressor or turbine.
[0021] The example low pressure turbine 46 has a pressure ratio
that is greater than about 5. The pressure ratio of the example low
pressure turbine 46 is measured prior to an inlet of the low
pressure turbine 46 as related to the pressure measured at the
outlet of the low pressure turbine 46 prior to an exhaust
nozzle.
[0022] A mid-turbine frame 57 of the engine static structure 36 is
arranged generally between the high pressure turbine 54 and the low
pressure turbine 46. The mid-turbine frame 57 further supports
various bearing systems 38 in the turbine section 28 as well as
setting airflow entering the low pressure turbine 46.
[0023] The core airflow C is compressed by the low pressure
compressor 44 then by the high pressure compressor 52 mixed with
fuel and ignited in the combustor 56 to produce high speed exhaust
gases that are then expanded through the high pressure turbine 54
and low pressure turbine 46. The mid-turbine frame 57 includes
vanes 59, which are in the core airflow path and function as an
inlet guide vane for the low pressure turbine 46. Utilizing the
vane 59 of the mid-turbine frame 57 as the inlet guide vane for low
pressure turbine 46 decreases the length of the low pressure
turbine 46 without increasing the axial length of the mid-turbine
frame 57. Reducing or eliminating the number of vanes in the low
pressure turbine 46 shortens the axial length of the turbine
section 28. Thus, the compactness of the gas turbine engine 20 is
increased and a higher power density is achieved.
[0024] The disclosed gas turbine engine 20 in one example is a
high-bypass geared aircraft engine. In a further example, the gas
turbine engine 20 includes a bypass ratio greater than about six
(6), with an example embodiment being greater than about ten (10).
The example geared architecture 48 is an epicyclical gear train,
such as a planetary gear system, star gear system or other known
gear system, with a gear reduction ratio of greater than about
2.3.
[0025] In one disclosed embodiment, the gas turbine engine 20
includes a bypass ratio greater than about ten (10:1) and the fan
diameter is significantly larger than an outer diameter of the low
pressure compressor 44. It should be understood, however, that the
above parameters are only exemplary of one embodiment of a gas
turbine engine including a geared architecture and that the present
disclosure is applicable to other gas turbine engines.
[0026] With reference to Prior Art FIG. 1B a seal assembly, such as
a carbon seal housing 110, piston ring 130, spring 140 and
cylindrical ID bore 120. A carbon seal housing 110 may comprise a
carrier configured to hold a piston ring 130. The piston ring 130
may be a torus, and/or a slotted torus. The piston ring 130 may be
configured to create seals. For instance, a fluid-tight seal may be
created between a first surface 134 of the piston ring 130 and a
first surface 122 of the cylindrical ID bore 120. The piston ring
130 may be configured to seal air from entering a bearing
compartment. A fluid-tight seal may be created between a second
surface 136 of the piston ring 130 and a first surface 112 of the
carbon seal housing 110.
[0027] These components may reciprocate axially and/or experience
vibration. These components may also experience radial eccentricity
which may involve components moving off-center. The size of gap B
may increase between the carbon seal housing 110 and the
cylindrical ID bore 120, at least with respect with a portion of
the carbon seal housing 110, in response with this radial
eccentricity and/or vibration. The size of gap A is constant. As
the size of gap B increases, spring 140 tends to travel in concert
with the carbon seal housing 110. This leads to a first face 142 of
spring 140 being off-center with respect to a third face 132 of
carbon seal housing 110. Having low values of face coverage may
cause wave spring distortion. This could negatively impact the
function and performance of the seal assembly and associated
engine.
[0028] According to various embodiments and with reference to FIGS.
2A-2E, a radial coverage piston ring groove arrangement seal
assembly is disclosed. The seal assembly may comprise a carbon seal
housing 210, a piston ring 230, spring 240 and cylindrical ID bore
220. The carbon seal housing 210 may comprise a carrier configured
to hold a piston ring 230. The piston ring 230 may be a torus,
and/or a slotted torus. The piston ring 230 may at least partially
circumferentially wrap around a cylindrical ID bore 220. The piston
ring 230 may be configured to create seals. For instance, a
fluid-tight seal may be created between a first surface 234 of the
piston ring 230 and a first surface 222 of the cylindrical ID bore
220. The piston ring 230 may be configured to seal air from
entering the bearing compartment. A fluid-tight seal may be created
between a second surface 236 of the piston ring 230 and a first
surface 212 of the carbon seal housing 210. A portion of the carbon
seal housing 210 may circumferentially wrap around both the piston
ring 230 and a portion of the cylindrical ID bore 220. Piston ring
230 may be made from any suitable material, such as cast iron,
steel, a non-metallic material, carbon graphite and/or the like.
Spring 240 may be any spring configured to properly position piston
ring 230 within carbon seal housing 210. According to various
embodiments, spring 240 may be a wave spring. A wave spring
(sometimes referred to as a coiled wave spring or a scrowave
spring), is a generally flat cylindrical article of material,
similar to a washer, to which waves are added to impart a spring
effect. The number of turns and waves can be adjusted to produce a
weaker or a stronger force.
[0029] According to various embodiments and reference to FIG. 2E,
piston ring 230 may be shaped such that its shape renders it
difficult or impossible to install in an incorrect orientation. For
instance, first step 215 of carbon seal housing 210 may extend in
such as manner as to physically interfere with an OD (bottom)
surface 213 of piston ring 230 should piston ring 230 be attempted
to be inserted within carbon seal housing 210 backwards.
Additionally, should spring 240 be attempted to be inserted
contacting second surface 236 rather than third face 232, piston
ring 230 will be physically restricted from insertion within carbon
seal housing 210 due to interference with first step 215 and/or
second step 218.
[0030] According to various embodiments, third face 232 of piston
ring 230 may be longer measured from the inner diameter to the
outer diameter that the length of spring 240 measured from the
inner diameter to the outer diameter. For instance, third face 232
of piston ring 230 may be longer than a first face 242 of spring
240. This may increase coverage and contact between the piston ring
230 and the spring 240, particularly, in response to a scenario
where the carbon seal housing 210 has bottom contacted at one
circumferential location (see FIG. 3 for an example of the carbon
seal housing 210 has bottom contacted at one circumferential
location). Third face 232 of piston ring 230 is radially longer
than third face 132 of piston ring 130.
[0031] According to various embodiments, second step 218 of the
carbon seal housing 210 may be sized such that spring 240 is
restricted from entering gap C. Stated another way, a width of the
second step is sized to prevent the spring from entering a gap
adjacent to the second step formed between the piston ring and the
carbon seal assembly. For instance, the width of second step 218 is
greater than about half the height of spring 240. Spring 240 is
taller, axially, than spring 140 (see axis X-X').
[0032] According to various embodiments and with reference to FIG.
3, a scenario where the carbon seal housing 210 has bottom
contacted at one circumferential location is depicted. In this way,
gap B' is about doubled as compared to gap B as shown in FIG. 2E
and gap A is maintained (as a constant size) from its size in FIG.
2E. Spring 240 has traveled away from cylindrical ID bore 220 with
the carbon seal housing 210. A high percentage of radial coverage
between third face 232 of piston ring 230 and first face of spring
240 may be maintained as compared with conventional methods. For
instance, radial coverage between third face 232 of piston ring 230
and first face of spring 240 is no less than about 66% coverage of
first face 242 of spring 240.
[0033] A modified ring groove geometry that creates 2 distinct
cavities or steps 215, 218 for the piston ring 230 and spring 240
is described herein. This concept provides a separate groove cavity
for the spring 240 (step 218), independent of the clearance cavity.
This modified ring groove geometry increases first face 242
coverage and reduces exposure risk for eccentricity of spring 240
to piston ring 230, to avoid potential disengagement and improve
function and performance of the seal assembly and engine. These
improvements are achieved while maintaining other design
constraints such as resistance to incorrect installation/assembly
and desired clearances.
[0034] Advanced, high-performance engines would benefit from
improved performance main shaft bearing compartment seals while
also meeting more aggressive cost, weight, size and reliability
metrics. Improved capability main shaft bearing compartment carbon
seals tend to meet the increased demands of next generation
high-performance engines. Carbon seals enable the engine and
bearing compartment to function with minimal impact on Thrust
Specific Fuel Consumption (TSFC), the Thermal Management System
(TMS) and the Lubrication System. Current and future engine
programs would benefit from seals with improved wear.
[0035] Benefits, other advantages, and solutions to problems have
been described herein with regard to specific embodiments.
Furthermore, the connecting lines shown in the various figures
contained herein are intended to represent exemplary functional
relationships and/or physical couplings between the various
elements. It should be noted that many alternative or additional
functional relationships or physical connections may be present in
a practical system. However, the benefits, advantages, solutions to
problems, and any elements that may cause any benefit, advantage,
or solution to occur or become more pronounced are not to be
construed as critical, required, or essential features or elements
of the inventions. The scope of the inventions is accordingly to be
limited by nothing other than the appended claims, in which
reference to an element in the singular is not intended to mean
"one and only one" unless explicitly so stated, but rather "one or
more." Moreover, where a phrase similar to "at least one of A, B,
or C" is used in the claims, it is intended that the phrase be
interpreted to mean that A alone may be present in an embodiment, B
alone may be present in an embodiment, C alone may be present in an
embodiment, or that any combination of the elements A, B and C may
be present in a single embodiment; for example, A and B, A and C, B
and C, or A and B and C. Systems, methods and apparatus are
provided herein. In the detailed description herein, references to
"one embodiment", "an embodiment", "various embodiments", etc.,
indicate that the embodiment described may include a particular
feature, structure, or characteristic, but every embodiment may not
necessarily include the particular feature, structure, or
characteristic. Moreover, such phrases are not necessarily
referring to the same embodiment. Further, when a particular
feature, structure, or characteristic is described in connection
with an embodiment, it is submitted that it is within the knowledge
of one skilled in the art to affect such feature, structure, or
characteristic in connection with other embodiments whether or not
explicitly described. After reading the description, it will be
apparent to one skilled in the relevant art(s) how to implement the
disclosure in alternative embodiments.
[0036] Furthermore, no element, component, or method step in the
present disclosure is intended to be dedicated to the public
regardless of whether the element, component, or method step is
explicitly recited in the claims. No claim element herein is to be
construed under the provisions of 35 U.S.C. 112(f), unless the
element is expressly recited using the phrase "means for." As used
herein, the terms "comprises", "comprising", or any other variation
thereof, are intended to cover a non-exclusive inclusion, such that
a process, method, article, or apparatus that comprises a list of
elements does not include only those elements but may include other
elements not expressly listed or inherent to such process, method,
article, or apparatus.
* * * * *